1. Field
Embodiments of the present invention relate to an organic light emitting display device and a driving method thereof.
2. Discussion of Related Art
Recently, a variety of flat panel displays that makes it possible to reduce the faults, the weight, and the volume of cathode ray tubes, has been developed. Typical flat panel displays include liquid crystal displays, field emission displays, plasma display panels, and organic light emitting display devices, etc.
The organic light emitting display device of the flat panel display devices displays an image using organic light emitting diodes that emit light by the recombination of electrons and holes, and has high response speed, and is driven at low power consumption.
In general, the organic light emitting display devices are classified into passive matrix organic light emitting display devices (PMOLEDs) and active matrix organic light emitting display devices (AMOLEDs), in accordance with the method of driving the organic light emitting diodes.
The active matrix organic light emitting display device includes a plurality of scan lines, a plurality of data lines, a plurality of power source lines, and a plurality of pixels coupled with the lines and arranged in a matrix. Each of the pixels typically includes an organic light emitting diode, a driving transistor for controlling the amount of current supplied to the organic light emitting diode, a switching transistor for transmitting a data signal to the driving transistor, and a storage capacitor for maintaining a voltage of the data signal.
The active matrix organic light emitting display device has the advantage of consuming low power, but has a problem that display is not uniform because the magnitude of current flowing through an organic light emitting element is changed due to a voltage difference between a gate and a drain of a driving transistor that drives the organic light emitting element, that is, a threshold voltage difference between the driving transistors in different pixels.
That is, properties of the transistors included in pixels are changed by variables in the manufacturing process, and accordingly, the threshold voltage difference of the driving transistors exists between the pixels. Currently, a compensating circuit that can compensate for the threshold voltage of the driving transistors is used to reduce the non-uniformity between the pixels.
The compensating circuit, however, additionally includes a plurality of transistors, capacitors, and signal lines for controlling the transistors. Therefore, the pixel including the compensating circuit has a problem that the aperture ratio is decreased and the possibility of defect increases.